The present invention relates to a fuel vent valve located on the upper portion of a fuel tank. The fuel vent valve includes a communication passage through which fuel vapor from inside the tank is allowed to pass. In particular, the present invention relates to the fuel vent valve providing a function that prevents fuel from spilling out from a filler neck.
A typical fuel vent valve includes a casing body, which includes a valve chamber and a communication passage extending between the inside and outside of the fuel tank, a float, which is located in the valve chamber and moved up and down in response to the fuel level in the fuel tank, and an upper valve member located above the float.
The typical fuel vent valve is closed in two steps in response to a rising fuel level when the fuel tank is filled. The two step valve closing prevents the pressure of the fuel tank from increasing suddenly. Thus, fuel over-flow or spilling at the fill opening is prevented.
If the upper valve member in such a valve is pushed up by a flow of fuel vapor and closes the communication passage when fuel vapor flows strongly from the fuel tank toward the communication passage through the valve chamber, then fuel over-flow cannot be prevented. Also, the load of the upper valve member is set according to the modulus of elasticity of a spring or rubber member, therefore, there are many processes involved in setting up and assembling the upper valve member.